Fabric softening compositions, and especially liquid fabric softening compositions, have long been known in the art and are widely utilized by consumers during the rinse cycles of automatic laundry operations. The term "fabric softening" as used herein and as known in the art refers to a process whereby a desirably soft hand and fluffy appearance are imparted to fabrics.
Rinse-added fabric softening compositions normally contain perfumes to impart a pleasant odor to the treated fabrics. It is desirable to have improved perfume retention for extended odor benefits.
Perfume delivery via the liquid rinse added fabric conditioning compositions of the invention in automatic laundry washers is desirable in two ways. Product malodors can be covered by the addition of even low levels of free perfume to the softener composition, and free perfume can be transferred onto fabrics with the softener actives in the rinse cycle. Present technologies add free perfume directly into the softener compositions independent of the other softener components, or in microcapsules formed, e.g., by coacervation techniques. Such encapsulated perfume can deposit on fabric in the rinse and be retained after the drying process for relatively long periods of time. However, such microcapsules that survive the laundry processing are often difficult to rupture, and free perfume that is released after the capsules rupture does not provide a noticeable rewet odor benefit.
Addition of free perfume into the softener composition allows the perfume to freely migrate creating an unstable condition and free perfume deposited on fabric dissipates fairly quickly in the drying cycle and when the fabrics are stored. If one wishes to have the perfume on fabric to last longer in storage or during wearing, it usually requires deposition of more perfume onto fabric in the laundry process. Higher deposition typically requires starting with an undesirably high level of perfume in the product and the resulting initial fabric odor is usually too strong. There have been many previous attempts to protect perfume to prevent excessive odor in fabric care products and on the fabrics themselves immediately after the washing cycle is completed, while having a delayed release of perfume from the fabrics when they are being used.
Compositions containing cationic nitrogenous compounds in the form of quaternary ammonium salts and/or substituted imidazolinium salts having two long chain acyclic aliphatic hydrocarbon groups are commonly used to provide fabric softening benefits when used in laundry rinse operations (See, for example, U.S. Pat. Nos.: 3,644,203, Lamberti et al., issued Feb. 22, 1972; and 4,426,299, Verbruggen, issued Jan. 17, 1984, said patents being incorporated herein by reference; also "Cationic Surface Active Agents as Fabric Softeners," R. R. Egan, Journal of the American Oil Chemists' Society, January 1978, pages 118-121; and "How to Choose Cationics for Fabric Softeners," J. A. Ackerman, Journal of the American Oil Chemists' Society, June 1983, pages 1166-1169).
Quaternary ammonium salts having only one long chain acyclic aliphatic hydrocarbon group (such as monostearyltrimethyl ammonium chloride) are less commonly used because for the same chain length, compounds with two long alkyl chains were found to provide better softening performance than those having one long alkyl chain. (See, for example, "Cationic Fabric Softeners," W. P. Evans, Industry and Chemistry, July 1969, pages 893-903). U.S. Pat. No. 4,464,272. Parslow et al., issued Aug. 7, 1984, incorporated herein by reference, also teaches that monoalkyl quaternary ammonium compounds are less effective softeners.
Another class of nitrogenous materials that are sometimes used in fabric softening compositions are the nonquaternary amide-amines. A commonly cited material is the reaction product of higher fatty acids with hydroxyalkylalkylenediamines. An example of these materials is the reaction product of higher fatty acids and hydroxyethylethylenediamine (See "Condensation Products from .beta.-Hydroxyethylethylenediamine and Fatty Acids or Their Alkyl Esters and Their Application as Textile Softeners in Washing Agents," H.W. Eckert, Fette-Seifen-Anstrichmittel, September 1972, pages 527-533). These materials are usually cited generically along with other cationic quaternary ammonium salts and imidazolinium salts as softening actives in fabric softening compositions. (See U.S. Pat. Nos. 4,460,485, Rapisarda et al., issued Jul. 17, 1984; 4,421,792, Rudy et al., issued Dec. 20, 1983; 4,327,133, Rudy et al., issued Apr. 27, 1982, all of said patents being incorporated herein by reference). U.S. Pat. No. 3,775,316, Berg et al., issued Nov. 27, 1973, incorporated herein by reference, discloses a softening finishing composition for washed laundry containing (a) the condensation product of hydroxyalkylalkylpolyamine and fatty acids and (b) a quaternary ammonium compound mixture of (i) from 0 % to 100% of quaternary ammonium salts having two long chain alkyl groups and (ii) from 100% to 0% of a germicidal quaternary ammonium compound of the formula [R.sup.5 R.sup.6 R.sup.7 R.sup.8 N].sup.+ A.sup.- wherein R.sub.5 is a long chain alkyl group, R.sub.6 is a member selected from the group consisting of arylalkyl group and C.sub.3 -C.sub.18 alkenyl and alkadienyl containing one or two C=C double bonds, R.sub.7 and R.sub.8 are C.sub.1 -C.sub.7 alkyl groups, and A is an anion. U.S. Pat. No. 3,904,533, Neiditch et al., issued Sept. 9, 1975, incorporated herein by reference, teaches a fabric conditioning formulation containing a fabric softening compound and a low temperature stabilizing agent which is a quaternary ammonium salt containing one to three short chain C.sub.10 -C.sub.14 alkyl groups; the fabric softening compound is selected from a group consisting of quaternary ammonium salts containing two or more long chain alkyl groups, the reaction product of fatty acids and hydroxyalkyl alkylene diamine, and other cationic materials.